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#include <bits/stdc++.h>

using namespace std;

#define ll long long 
#define ld long double

void solve () {
    int n;
    cin >> n;

    vector<vector<int>> g(n + 1);

    for (int i = 1; i <= n; i++) {
        string s;
        cin >> s;
        for (int j = 0; j < i; j++) if (s[j] == '1') {
            g[i].push_back(j + 1);
            g[j + 1].push_back(i);
        }
    }

    pair<int, pair<int, int>> total_max = {-1, {-1, -1}};
    for (int k = 1; k <= n; k++) {
        vector<int> d(n + 1, 1e9 + 1);
        d[k] = 0;
        queue<int> q;
        q.push(k);
        pair<int, int> maxi = {0 , 0};
        while (q.size()) {
            int v = q.front();
            q.pop();
            for (int u : g[v]) {
                if (d[u] == 1e9 + 1) {
                    d[u] = d[v] + 1;
                    maxi = max(maxi, make_pair(d[u], u));
                    q.push(u);
                }
            }
        }

        total_max = max(total_max, make_pair(maxi.first, make_pair(maxi.second, k)));
    }

    int rem  = total_max.second.second;
    for (int u : g[rem]) {
        g[total_max.second.first].push_back(u);
        g[u].push_back(total_max.second.first);
    }

    total_max = {-1, {-1, -1}};
    for (int k = 1; k <= n; k++) {
        if (k == rem) continue;
        vector<int> d(n + 1, 1e9 + 1);
        d[k] = 0;
        queue<int> q;
        q.push(k);
        pair<int, int> maxi = {0 , 0};
        while (q.size()) {
            int v = q.front();
            q.pop();
            maxi = max(maxi, {d[v], v});
            for (int u : g[v]) {
                if (u == rem) continue;
                if (d[u] == 1e9 + 1) {
                    d[u] = d[v] + 1;
                    q.push(u);
                }
            }
        }

        total_max = max(total_max, {maxi.first, {maxi.second, k}});
    }

    cout << total_max.first << "\n";

}

int main () {
    ios_base::sync_with_stdio(NULL);
    cin.tie(0);

    int t;
    cin >> t;
    while (t--) solve();
    return 0;
}